1. Field of the Invention
An apparatus and method for establishing a plurality of tool elements in a desired configuration in relation to a workpiece surface are disclosed.
2. Description of the Prior Art
In the production of modern gas turbine engines, critical components subjected to high stress and temperature are oftentimes provided with internal cooling. For example, certain parts such as turbine blades or vanes are produced by sophisticated casting techniques to have an internal cooling cavity. After casting, holes are drilled by electrical discharge or electrochemical techniques in the leading or trailing edges of the airfoil section of the blade or vane to communicate with the cavity and provide a path for the circulation of cooling air therethrough. However, the drilling of such cooling holes has been fraught with difficulty because these edges bow or curve along the airfoil section of the part to achieve the desired aerodynamic effect. The problem has been one of proper placement and support of the drilling elements, such as electrodes, in a configuration corresponding and in precise relation to the curvature of the edge. As evidenced by U.S. Pat. Nos. 3,767,555; 3,803,015; 3,827,965; and 3,842,840, prior art workers have relied primarily on drilling element guides of a rigid, solid nature having prealigned guide holes therein for proper placement and support of the drilling elements.
If holes are to be drilled on the centerline of the curved edge of the blade or vane; for example, where it is necessary to maintain a minimum edge wall thickness, further difficulty is encountered as a result of casting or other part tolerances. These tolerances result in substantial variations from part to part in the thickness and amount of bow or curvature of the edge to be drilled and, thus, make positioning of the drilling elements in a configuration corresponding and in precise relation to the centerline of the curved edge of each part extremely difficult.